A semiconductor integrated circuit such as a large scale integrated circuit (LSI) is typically increased in importance of protecting an internal circuit (hereinafter, referred to as a protected circuit) having a predetermined function from a surge that occurs in a power supply line, in association with miniaturization and voltage reduction of the semiconductor integrated circuit.
The power supply line voltage is drastically increased by electrostatic discharge (ESD) with respect to an external terminal of the power supply line, namely, an ESD surge is well-known as a representative of the surge that occurs in the power supply line.
A device or a circuit for ESD protection is integrated together with the protected circuit on a semiconductor substrate in order to prevent the protected circuit from being damaged by a high-voltage pulse that occurs in the external terminal by the ESD surge.
As the device or circuit for ESD protection, for example, a GGMOS (gate grounded MOS), a thyristor, and an RCMOS are well-known. Although the device or circuit for ESD protection is properly used depending on a purpose, an ESD protection circuit having an RCMOS configuration that is relatively simple in design is often used in recent years (for example, refer to PTL 1 and NPTL 1).